Various types of depth indicators are known in the prior art for providing information regarding the depth of liquid in a well or storage tank. Problems have arisen, however, in the viewing of the depth indication given by such devices because of their relative complexity. In particular, it is difficult to read such devices from remote positions. Some such prior art apparatus provide a numerical indication of the depth of fluid on a counter or a tape, or by moving a pointer relative to a scale, and such indicators are generally located within a housing that must be opened for viewing, requiring the presence of the viewer at the well or tank. Viewing becomes even more difficult after dark since some form of lighting must be provided in order to view the counter or scale.
Another problem in the art of monitoring the depth of a well is automatically stopping the withdrawal of water from the well when the depth of water in the well reaches a certain minimum level. Prior art devices for accomplishing this purpose have generally included a means for stopping the well pump motor when the minimum level is reached. This can cause a foot valve normally associated with the pump to leak, allowing the pump to become unprimed.